The invention relates to a tail section for a multiple chain drag conveyor system utilized to transport and move feed, grain, cereals or other material over extended distances.
An important aspect of the conveying of large quantities of granular material is the ability to move that material over extended distances from an off-loading area to a storage area in an automated manner. In order to accomplish this, several types of conveyors have been designed and are presently being employed. One such type is a box conveyor which has a succession of boxes affixed to an endless chain. As the boxes pass under a loading platform, they are filled with grain or similar material, the timing being such that each box is under the loading spout for a predetermined period of time sufficient to fill it as it passes. The boxes are conveyed along to the storage area where they empty their contents into the storage bin.
Another form of conveyor is a chain drag conveyor such as the ones built by Tramco Metal Products, Inc. of Wichita, Kans. under the trade name "TRAMCO CHAIN CONVEYORS." The larger capacity chain drag conveyors require that two or more chains be employed. Each chain is carried on a sprocket in a tail section of the conveyor. The chain extends all the way to a head section of the conveyor which is situated in the storage area. A number of paddles or a flight are secured to the chains and serve to push the grain or similar material along the conveyor path from the loading area to the storage area. The sprockets are mounted in the tail section on a single shaft. The use of a single shaft tail section for a multiple chain drag conveyor raises several problems. For instance, if a chain break occurs, the shaft and associated sprockets will continue to turn because of the inability to sense breakage of a single chain. As a result, the head section of the conveyor can be severely damaged, and the second chain, which did not break, may also suffer injury.
Another problem is that whenever one portion of a chain must be replaced, it is difficult to adjust and tension the two chains relative to one another, because as a chain is used, it tends to stretch slightly. Therefore, replacing a section of a chain or an entire chain will result in a disparate length between the two chains. Because adjustments are essentially in one plane, any tension on one side of the shaft in order to tighten or loosen that chain will result in the shaft being displaced from the perpendicular to the direction of motion of the chains. Thus, by having both carry sprockets on a common tail shaft take-up system, the replacement of only one chain or a portion of a chain creates a number of problems. However, cost and other factors make it undesirable to replace both chains if there is damage to only one.
Another problem is that by carrying both sprockets on a single shaft, any jam or delay on one flight of the conveyor may result in damage to the sprocket and chain carrying the other flight, as well as damage to the head section which powers the multiple drag chain configuration. If the damage is sufficiently severe, the objective of conveying large quantities of granular material from an off-loading area to a storage area is defeated.
An additional problem is that use of a single shaft for a multiple chain drag conveyor may cause injury to other parts of the conveyor assembly, particularly over extended lengths. The inability properly to tension and adjust the chains causes additional wear and tear and accordingly limits the dependability of the conveyor system and shortens its useful life.
A further and particularly significant problem resulting from the use of a single tail shaft to carry multiple chains and sprockets arises because of the nature of the automation. In particular, if one chain becomes damaged or breaks, the entire conveyor assembly frequently must be cleared and, because both chains are on a single shaft it becomes difficult to remove the damaged chain. This is particularly true if the grain loading mechanism continues to pour grain into the tail section, expecting that it will be carried off. It is not only costly and time consuming, but dangerous to have a build-up of grain at one end of the conveyor with concomitant increase in dust, a highly flammable and serious situation, not to mention the loss of grain resulting from the spillage.